Test C: DTC P0579 or DTC P0581 - Speed Control Switch Circuit Failure

PINPOINT TEST C: DTC P0579 OR DTC P0581 - SPEED CONTROL SWITCH CIRCUIT FAILURE

C1-C2:

C2-C4:

C4-C6:

C6-C8:

C9-C11:

Normal Operation
The powertrain control module (PCM) sends a signal, which passes through the clockspring, through circuit 151 (LB/BK) to the speed control switches. The return signal is sent through circuit 848 (DG/OG) and the clockspring.

DTC P0579 - may set when the speed control switch circuits are open, shorted to voltage or shorted to ground.

DTC P0581 - sets when the speed control switch circuits are shorted to voltage or open.

Possible Causes
- Circuit 151 (LB/BK) open, short to voltage or ground
- Circuit 848 (DG/OG) open, short to voltage
- Clockspring
- Speed control switch
- Horn switch wiring harness
- PCM